Models 3, 4, 6, and 8 exhibited no laminar separation. The flow regimes, measured by 

 the hot film gages, are given in Figures 9 through 12. Experimental data have been compared 

 with predicted spatial amplification ratios of disturbance as calculated by linear stability 

 theory. These ratios were calculated using a computer program developed at the Center, 

 DABL (disturbance amplification in boundary layers).* 12 In Figures 9 through 12, predictions 

 corresponding to spatial amplification ratios of e 3 , e 5 , e 7 , e 9 , e , and e are compared with 

 flow regimes. The results given in these Figures fail to show a single relationship between the 

 measured flow properties in the transition regions of the four models and the corresponding 

 computed spatial amplification ratios. Correlations of amplification factors with flow regimes 

 vary both with forebody shape and Reynolds number. Table 5 gives the principal results 

 obtained for each model. 



It has been assumed in this report that flow transition originates with the start of 

 turbulent bursting (Type 3 flow of Figure 7). The critical amplification factor correlating 

 with this flow transition condition varies considerably from model to model and to a lesser 

 extent, on individual models, with changes in Reynolds number. On Model 3 this variation is 

 estimated to change from e 12 at low values of R D to e 8 at the highest values of R D . The 

 corresponding values on Model 4 are from e 11 to e 9 ; on Model 6, from e 12 to e 10 . The data 

 available for Model 8 indicate a nearly constant value of e 7 . However, due to the failure of 

 a hot film probe, data at the critical location at the higher values of R D are lacking for this 

 model. 



RESISTANCE RESULTS 



The C R 's obtained for each model are plotted in Figures 13a through 13i as functions of 

 Reynolds number R L . The dotted line in each figure represents the faired mean values of C R 

 obtained from all of the experiments with a given model, both with and without turbulence 

 stimulators installed. The solid lines roughly define zones of scatter at Reynolds numbers 

 greater than R L = 10 7 . The scatter ranges as much as ±0.050 • 10" 3 about the mean value 

 for some of the models. 



*Stability results from this program for Models 3 and 4 (Figures 9 and 10) differ from stability results given 

 in Reference 1 for the same two models (Figures 6 and 7 of that Reference). Results given in Reference 1 

 were obtained by hand calculations, using charts from Reference 6. The discrepancy no doubt results from 

 approximations involved in using interpolations required in determining the amplification factor, using hand 

 calculations. 



von Kerczek, C. and N.C. Groves, "Disturbance Amplification in Boundary Layers," paper in preparation. 



16 



